The invention relates generally to impact absorbing struts. More particularly, the invention relates to a shock absorbing device such as that interconnecting the chassis and bumper of a motor vehicle for protecting motor vehicles from damage by low speed collisions.
It is known to install piston and cylinder type fluid filled shock absorbers between a bumper and the chassis of an automotive vehicle for dissipating the energy of a low speed collision without serious damage to the vehicle. A liquid is driven in the known arrangements by the force of the impact through a throttling passage in which the kinetic energy of the flowing viscous liquid is converted to thermal energy. If a resilient element such as a spring or a cushion of gas under pressure is provided, it serves mainly to expel the piston from the cylinder after the impact and thereby to restore the original condition of the shock absorber if the latter is not damaged in the collision. In one prior art arrangement, compression of a gas within the shock absorber is simultaneously provided for, along with throttling of a viscous liquid through a port, for the purpose of mitigating the temperature sensitivity of this type of shock absorber.
In other known shock absorbing arrangements, a shock absorber defines a fluid cylinder including one or more blowout plugs. Upon impact, the plugs are blown out of their ports and the energy of the impact is absorbed by throttling a viscous fluid through the ports. In other shock absorbers of the type in which a viscous fluid is ejected from a shock absorber cylinder, the shock absorber cylinder is at least partially surrounded by a resilient bellows which accommodates the displaced liquid upon impact and urges the liquid back into the cylinder through the throttling ports after the impact.